Copy of letter sent from Cecelia McKie to 'Mr. Luyndyk', as recorded in the letter, regarding Santo Tomas Internment Camp internee B. Luyendik, recorded in the letter as 'Bernard Luyndyk'. Letter contains transcribed message broadcast to parents from internee on Radio Tokyo.

From Introduction: "The investigations presented in this bulletin have been undertaken by the bureau with a view to a better understanding of the conditions which confront the producer of commercial feldspar and also with the object of determining wherein the various deposits of feldspar differ."